Intermittent Ticking '09 Yukon

[harbison]

2009 Yukon XL 255K 5.3L has developed an intermittent engine ticking. Tried Liqui-Moly engine flush. Had AFM deleted at 200K, replaced lifters. Any ideas?

 

[swathdiver]

2009 Yukon XL 255K 5.3L has developed an intermittent engine ticking. Tried Liqui-Moly engine flush. Had AFM deleted at 200K, replaced lifters. Any ideas?

Well, where's it coming from? Could it be an exhaust leak or is it in the head or under a rocker cover, etc.?